ORNL RAD, Oak Ridge, Tennessee, USA
ORNL, Oak Ridge, Tennessee, USA
The Spallation Neutron Source (SNS) Linear Accelerator (Linac) delivers a high power proton beam (>1 MW) for neutron production with high neutron availability (>90%). For beam acceleration, the Linac has both normal and super conducting RF sections, with the Super Conducting Linac (SCL) portion providing the majority of beam acceleration (81 of 96 RF cavities are super conducting). Operationally, the goal is to achieve the highest possible beam energy by maximizing SCL cavity RF gradients, but not at the expense of cavity reliability. One mechanism that has negatively impacted both SCL cavity RF gradients and reliability is beam lost into the SCL due to malfunctions of upstream components. Understanding the sources and impacts of errant beam on SCL cavity performance will be discussed.
ORNL, Oak Ridge, Tennessee, USA
ORNL RAD, Oak Ridge, Tennessee, USA
The SNS uses charge exchange injection to minimize losses during the accumulation of the accelerated beam in the ring. A stripper foil implements this by removing the electrons from the high intensity H− beam coming from the linac. At a beam power of 1.2 MW, the foil lasts for many weeks, sometimes months. However, given the upgrade to 2.8 MW, it is important to know the current temperature of stripper foil in order to estimate its lifetime for the new beam power and beam size. In this paper, we discuss several methods to measure the temperature of stripper foil exposed to current operating conditions of the SNS accelerator. Given the high radiation in the vicinity of the foil, the uncertainty in the foil's emissivity, and available resources, we chose a two-wavelength pyrometer that is located 40 m from the foil. The pyrometer is composed of two mirrors, a refracting telescope, and two photodiodes. We present the calibration data and the temporally resolved measurements made with this pyrometer.